


turn all the mirrors around

by onceuponachildhood



Category: Undertale (Video Game)
Genre: Gen, Minor Violence, Pacifist Route, Possession, Quiet Badassery is my jam, Spoilers, Timeline Shenanigans
Language: English
Status: Completed
Published: 2015-11-16
Updated: 2015-11-22
Packaged: 2018-05-02 00:10:30
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,260
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5226431
Author URL: https://archiveofourown.org/users/onceuponachildhood/pseuds/onceuponachildhood
Summary: <blockquote class="userstuff">
              <p>Flowey doesn't seem to be able to fool the people that know Sans the best | UT Possession AU</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> special thanks to [sushi](http://sushinfood.tumblr.com/) for ripping my still-beating heart out of my chest with this au.

**Notes for the Chapter:**

> recommended music is [a piano arrangement](https://www.youtube.com/watch?v=qx6KpdolfEY&feature=youtu.be?) of megalovania.

* * *

Flowey strode forward comfortably in Sans’s body. Without Sans constantly fighting him, it had to have been easier. Sans had been fighting him for hours. Sans was… exhausted. He’d never have expected something so internal to be so tiring; fighting Flowey long enough to warn his brother had been almost impossible. It felt like it had taken everything he had. Sans had been too tired to struggle, forced to watch as Flowey had used his body to jump to Snowdin and threaten Grillby. He’d known his old friend could take care of himself, but it was horrifying to watch, all the same.

“Hmmmm,” Flowey said aloud, his voice echoing in Sans’s own head. “It feels like you’re still fighting me, Sans. I think we’re gonna have to put a stop to that behavior right now.” Flowey chuckled. “I wonder who else you care about I might be able to get to.” Flowey laughed again, low and self-satisfied. Sans was beginning to hate the sound of his own laugh. “Someone a little more defenseless than that old hothead.” There was a pause in which all Sans could hear was his own controlled footsteps. “I know! Let’s go visit the good Doctor Alphys. I think she’s about as harmless as they come, hmmm? Defenseless.  ** _Weak_**. She’s the perfect prey.”

“no no no no no no-”

“No?” Sans hadn’t even realized he’d spoken aloud. “Well that settles it, then. Next stop, Hotland. I’ve got-” Flowey snickered. “Oh, Sans, you’ll appreciate this one. I’ve got a bone to pick with her.”

Sans felt sick.

“Now, Sans, be a good toy… and… jump…” But instead of forcing him to jump, Flowey seethed. Sans felt magic surge around him- his own and that of Flowey- and he tried to figure out what had set the flower off. Directly ahead of them, gently patting a moldsmal before it wiggled away, was Frisk. It felt at once like Flowey tightened his grip on Sans, vines tensing around his bones nearly to the breaking point. “Oh, this is even better.”

“frisk is just a kid you can’t-”

The vines tightened further. Sans did feel something snap, but Flowey wouldn’t even let him cry out. “Shut up. Frisk is a powerful soul and a being of determination.” Flowey chuckled, slipping into Sans’s voice easily. “ ** _it’s going to be so fun watching them die_**.”

Frisk looked up as Sans approached them. They offered a wide, welcoming smile that Sans would otherwise have enjoyed very much. As it was, he just hoped he could muster the strength to step in when Frisk needed him most. “hey, kiddo, how’s it going?” Frisk stood, bouncing a little in place. “that good, huh?” Frisk nodded and reached out to grab Sans’s hand. He felt the vines shrink back from his wrist a little- not enough for him to do anything, but enough that Frisk wouldn’t accidentally brush against them. “what, a date with papyrus wasn’t enough? you need both of us?”

Frisk squeezed his hand once and winked. They started walking, tugging Sans along behind them toward a secluded section of Waterfall.

At this rate they would do Flowey’s work for him. Sans tried to gather the energy to pull back, but all he could manage was a tight squeeze back at Frisk. The kid nodded once as they walked, though to themselves or to Sans he had no idea.

“hey, kiddo, where exactly are we going?” Frisk didn’t answer, still leading Sans and his pilot deeper into the uninhabited areas of Waterfall. Flowey pulled his hand away from Frisk and stopped walking. “listen, kiddo-” There was a sudden sickening shift in reality. When Frisk turned around, their face was aglow with the light spilling from their SOUL.  “hey, buddy, you’re not gonna fight your old friend sans, are you?”

“Give him back.” Flowey seemed as startled by Frisk’s sudden words as Sans himself was. Frisk spoke so rarely, it was easy to forget that they had a voice at all. It was soft from disuse, and high like a child’s voice usually was, but Frisk spoke with the authority of a monarch. “You have my friend. Give him back,  _Flowey_.”

The kid  _knew_  about- Flowey dropped all pretense, unfurling himself from where he hid in Sans’s bones. “Ohhh, so you figured me out, did you? That’s just peachy.”

“I didn’t go on a date with Papyrus in this timeline,” Frisk said quietly.

Sans’s body jerked back in surprise. Flowey curled around his skull a little; Sans could feel his grin getting wider against his own wishes. “And just what have you been doing resetting without telling me, you naughty child?”

Frisk didn’t answer the flower, but instead pulled out a knife that Sans didn’t even know they’d had. It looked wrong, gripped in Frisk’s tiny fingers. Frisk, who stopped to pet the moldsmals as they walked. Frisk, who’d made friends with every resident in Snowdin town. Frisk, who’d stepped around bones flung their way and offered a hand of peace. The knife in their hands looked wrong- so very wrong-

“f-frisk…”

“ ** _Quiet, you_**!” Flowey snapped another one of his bones, and this time he let Sans’s scream out. Frisk watched the whole scene with eyes far more hardened that Sans would have expected. “He’s awfully stubborn, this one.” Overlapping with Sans’s sobs, Flowey spoke as if nothing was wrong. “We both know you’re not Chara. You don’t have the guts to use that knife.”

The blade glittered in the light when Frisk shifted. Sans focused on that and not the nausea caused by the broken bones. Flowey didn’t seem to feel a thing. “You have my friend. I’m determined to get him back.”

* * *

 


	2. Chapter 2

**Notes for the Chapter:**

> recommended music is [a piano cover](https://www.youtube.com/watch?v=KeqrJ8rGZ34) of ghosts n' stuff

* * *

Flowey giggled. “Oh, you’re so determined, are you?”

“f-frisk…” Sans tried again. “run…”

Flowey slithered around his skull. It felt _awful_ , a headache brought to life in the form of a thorny snake. “He’s certainly worried about you, isn’t he, Frisk?” Flowey raised up a little; Frisk stood their ground. “More worried about you than you’ve ever been about him. Think of all the happy endings you’ve crushed beneath your heel because you weren’t satisfied.”

Sans thought of the strange photo in his lab. Had- had they really gotten out?

… had Frisk really sent them all back?

“Didn’t save everyone,” Frisk said quietly. Confirmation was a stone sinking in Sans’s nonexistent gut. “Asr-”

“ _ **D O  N O T  U S E  T H A T  N A M E**_.” Flowey did something to his broken bones- wrenched them, or twisted the breaks, or something. The only reason Sans didn’t collapse was because the flower held him up; the pain was so immediate that he still stumbled to one knee. A scream tore out of him, ragged and broken. “I think,” Flowey said, his voice clipped, “that you forget exactly what power I have, here. I’ll remind you using your ‘friend,’ if I must.” Flowey’s laugh shifted, took on a darker tone. “Unless you really don’t care about him as much as you said you do.”

Sans forced himself to look up. Frisk held the knife in their left hand, their eyes still cooler than Sans ever remembered seeing before. Their free hand was clasped in a fist against their chest, illuminated red by their SOUL. Sans watched as Frisk took their fist and moved it in a clockwise circle. Sans knew that sign.

 _oh, kiddo_. Their soft heart would be their downfall. “its okay, kiddo… leave me here…”

Flowey slapped Sans in the back of the skull with a leaf. It was so gentle, so incongruous with the flower’s earlier actions, that Sans cringed anyway. “That’s almost cute. He still thinks you’re worth protecting.” Flowey forced Sans to stand. “But we know the truth, don’t we Frisk? You’re not going to be satisfied until you can save everyone.”

Instead of answering, Frisk just kept looking at Flowey with those sad, serious eyes.

“Don’t look at me like that.” Sans could feel Flowey’s rage. It burned white-hot through his limbs, and alongside the vines it was easy for Flowey to grip control of Sans’s magic. Frisk kept staring, just… waiting. “You think you’re better than me, huh? You think you can win?”

Frisk shook their head. “Not better than anyone.” This time, when they shifted the knife, they stepped forward. “But I _will_ win.”

Flowey shrieked and lashed out wildly with Sans’s magic. A barrage of bones shot forward. Frisk dodged them all- far more agile that they’d been when facing Papyrus. Frisk hadn’t taken a single point of damage, and this only made Flowey angrier. He dug deeper into Sans. A few more of Sans's bones splintered under the pressure. With a surge of power that redoubled Sans’s nausea, Flowey summoned the Gaster Blasters.

Frisk stumbled backward, if only for a second.

“Oh, what’s this?” At the break in Frisk’s composure, Flowey seemed to feel more comfortable. “You’ve never seen **these** before? No, of course you haven’t, you goody-two-shoes.” Flowey giggled. “Don’t worry, you’re about to experience them firsthand.”

Frisk only had 20 HP. _Frisk only had 20 HP_. They wouldn’t be able to survive this attack. They wouldn’t be able to survive being clipped by this attack. Sans _struggled_. “kiddo…”

The sound of the blasters howling drowned out his voice.

* * *

Flowey summoned the Gaster Blasters.

Frisk’s expression tightened. They shifted their weight to the balls of their feet.

Sans had the strangest feeling of deja-vu.

The blasters went off, ripping a path of destruction through the soft turf of Waterfall. Frisk dodged, slipping into the safe space between the beams as if they’d known where it would be.

Flowey cackled. “Yes, yes! You’re so determined to save him, you’ll come back just so you can die and die and die.” The blasters trembled. “That strength, that determination- that’s going to be your downfall, Frisk.”

Frisk shook their head. “Give him _back_.”

“Still on about that, huh?” Flowey ran a leaf along Sans’s skull in a mockery of a tender gesture. Sans shuddered, unable to pull away. “Hmmm, I’m thinking… not.” The blasters shifted so that they created a new pattern. Flowey grinned. “Die.”

Frisk was obliterated in the blast.

* * *

Flowey summoned the Gaster Blasters.

Frisk’s eyes narrowed and they were moving before the blasters even had a chance to rip them apart.

Sans had the strangest feeling of deja vu.

Frisk dodged into the safe space between the blasters’ beams. Flowey didn’t even bother gloating, switching the blasters into a new pattern and firing again. Frisk dodged these too, looking more determined- and frankly, badass- than Sans had ever seen them before. “Give him back!” They shouted.

Frisk _never_ raised their voice.

Apparently this was a new thing for Flowey too, because he paused. “Hmph. What do you care?” Flowey chuckled, though it rang hollow. It was more of a facade than true enjoyment. “There’s nothing worthwhile in this bag of bones. Just sadness and disappointment.”

Frisk’s face _twisted_ , more angry than Sans had ever even imagined that he would see. “That’s not true,” Frisk retorted. “Sans is my fam- friend,” Flowey seemed to take note of the verbal stumble, but then, so did Sans. It warmed him like he hadn’t expected. Frisk shifted their grip on the knife, still keeping a wary eye on the blasters. “Papyrus and I love him, and he is worth everything to us. I’ll get him ba-”

With a snarl, Flowey activated the blasters.

* * *

There was no hesitation before Flowey summoned the Gaster Blasters.

Frisk was moving in the same second that they were firing, dodging blast after blast like they’d been hundreds of rounds with the attacks.

Sans had the strangest feeling of deja vu.

“Sans!” Frisk shouted, skidding to a stop just before the beam of one of the attacks. “Sans, please! I know you can hear me!”

_i can’t help you kid i cant help you i can’t fight back i_

_am_

**_weak_ **

_i_

_am_

**_worthless_ **

Frisk hit the ground and rolled beneath another attack. “It’s okay, Sans.” Frisk was… Frisk was crying. Sans could feel Flowey’s hesitation. “It’s okay if you can’t fight back.” Frisk smiled, tears streaming down their face. “I love you, Sans. Papyrus and I, we both love you so much. We’re gonna save you, Sa-”

The blasters roared along with Flowey.

* * *

Flowey summoned the blasters already activated, magic crackling through the air with the subtle scent of ozone.

Frisk was dipping to and fro to avoid the magic. “Just hold on, Sans. I know you can do it!”

Sans had the strangest feeling of-

Wait.

This was- he’d been in this timeline before. Flowey gripped his bones with enough force to leave splintering cracks all along his limbs. Frisk dodged attacks, but their eyes never left Sans. They looked- they looked _determined_ , jaw set and brow furrowed, but their love was still evident in their eyes. “Be quiet,” Flowey howled. “He belongs to me now. You can’t have him!”

“He doesn’t-” the blasters roared, and Frisk ducked- “belong-” another attack, but Frisk practically danced out of the way- “to anyone!”

Frisk was suddenly right in front of him, within arm’s reach, and they weeped so openly for Sans that he felt his SOUL might burst. “ _ **FRISK**_ -”

“I’m sorry,” Frisk said, and then they reached forward to plunge the knife into Sans’s eyesocket.

Flowey tried to pull back. With everything he had, with every bit of love he had for Papyrus and Frisk, Sans threw himself into controlling his own body and forced himself to hold still.

* * *

 


End file.
